This invention relates to a dispatching algorithm for controlling the movement of passenger cabs in a piston-type passenger conveying system.
Typically, passengers are moved between the floors in low rise buildings such as malls, etc., by escalators. Escalators are widely utilized in most malls. Most malls also incorporate a few elevators for moving passengers between floors. Elevators do not move as many passengers as quickly as an escalator, due to wait time, door opening time, dwell time, etc. Moreover, shoppers in a mall seem to prefer the escalator in that they move more quickly between the floors and can look around the mall while moving.
Statistics show that the average escalator moves a much higher number of passengers than the average elevator in such locations. However, escalators have down sides. As an example, escalators do not transport strollers, wheelchairs, etc. as easily as elevators. Recently, the assignee of the present application developed a piston-type passenger conveying system. In the piston system, a set of at least three cabs are utilized to move the cabs between the two floors. A control moves the cabs such that a cab is waiting at each floor at all times. Another cab is moving between the floors. Contrary to typical elevator systems, the cabs are moved based upon a control algorithm to be in desired locations, rather than being moved in response to passenger requests.
The piston system provides the main benefits of both the escalator and the elevator. The basic movement technology is elevator technology. However, passenger flow is continuous, and thus a higher number of passengers can move between the floors. The basic invention as described above is disclosed in U.S. patent application Ser. No. 09/571,769, entitled xe2x80x9cPiston-Type Passenger Conveying Systemxe2x80x9d, filed on even date herewith.
With such a system, real-world problems do arise. In one embodiment, a control for this system desirably dispatches four cabs between the floors such that each of the cabs are 90xc2x0 out-of-phase with each other. However, at times, a passenger could hold a door open, or some other incident could cause at least one of the cabs to be out-of-phase relative to a desired position. In the preferred embodiment of the piston system, the cabs are grouped in pairs, which are each at directly opposed positions in the cycle. Thus, if one of the pair is held open, both of the cabs in a pair will be out-of-phase relative to the desired positions. The above application also discloses different numbers of cabs from three to six, or more. The out-of-phase relationship changes as the number of cabs change. However, with any number, the above problems of being out-of-phase from a desired position can exist.
A system would be desirable to account for and correct this out-of-phase positioning.
In a disclosed embodiment of this invention, a system identifies an out-of-phase cab, and determines a corrective action. Typically, the door hold-open time for a cab is modified such that the cabs quickly move back to being in phase. The door hold-open time is the easiest variable to control.
In other features of this invention, specific algorithms are disclosed to achieve the adjustment such as described above. Further, a sleep mode is also disclosed for such a system. In the sleep mode, the piston system stops with at least one cab at each floor, until a passenger is sensed entering one of the cabs. When a passenger has entered the cab, the system moves back to its standard cycle. This is a separate and additional improvement over escalators. Escalators often have no sleep mode and will often use energy to run while empty for long periods of time. Some escalators do have a sleep mode, but most do not in the United States.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.